[Bug target/113652] Failed bootstrap on ppc unrecognized opcode: `lfiwzx' with -mcpu=7450

["linkw at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113652

Kewen Lin <linkw at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[14 regression] Failed      |Failed bootstrap on ppc
                   |bootstrap on ppc            |unrecognized opcode:
                   |unrecognized opcode:        |`lfiwzx' with -mcpu=7450
                   |`lfiwzx' with -mcpu=7450    |

--- Comment #9 from Kewen Lin <linkw at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #8)
> So t-float128 has this line:
> # Build the emulator without ISA 3.0 hardware support.
> FP128_CFLAGS_SW          = -Wno-type-limits -mvsx -mfloat128 \
> ...
> 
> Which gets added to some of the libgcc object files while compiling:
> $(fp128_softfp_obj)      : INTERNAL_CFLAGS += $(FP128_CFLAGS_SW)
> $(fp128_ppc_obj)         : INTERNAL_CFLAGS += $(FP128_CFLAGS_SW)
> 
> 
> The problem is CFLAGS gets added also. It seems like passing -mvsx enables
> some other instructions in GCC's code generation BUT does not enable it for
> the assembler ...

ah, just noticed that it's bootstrapping gcc. Stripping regression tag since I
don't think it's actually a regression as comments above.

I found that the libgcc_cv_powerpc_float128 checking can pass with -mcpu=7450
-mabi=altivec -mvsx -mfloat128, the assembler options are "-a32 -mppc -mvsx
-maltivec -mbig" is actually the same as what are used for the case #c5
compiling. So it looks that -mvsx is supposed to tell assembler to recognize
vsx instructions but somehow "lfiwzx" is not counted as vsx instruction.

More specifically "xvadddp" is recognized by assembler with -mvsx while
"lfiwzx" isn't.

$ cat t1.s
.machine "7450"
lfiwzx 1,0,9

$ cat t2.s
.machine "7450"
xvadddp 34,34,35

$ as -a32 -mppc -mvsx t1.s -o t1.o
t1.s: Assembler messages:
t1.s:2: Error: unrecognized opcode: `lfiwzx'
$ as -a32 -mppc -mvsx t2.s -o t2.o
$ echo $?
$ 0